1. Field of the Invention
The present invention relates to an airbag system comprising an airbag obtained by closing each of opposite end portions of a folded tubular metal tube with an end cap and attached to an attachment surface of a front pillar, the airbag system protecting a pedestrian by deploying the airbag along the front pillar with a gas produced by an inflator.
2. Description of the Related Art
Japanese Patent Application Laid-open No. 2002-283939 has made publicly known an airbag system for protecting a pedestrian which is configured so that: a folded airbag made of cloth is stored inside a pillar garnish for covering a front surface of a front pillar of an automobile; in collision with a pedestrian, a gas produced by an inflator is supplied to the airbag, and thus deploys the airbag along the front surface of the front pillar from a rip which is made when the pillar garnish breaks; and the pedestrian is protected with the airbag thus deployed.
In addition, Japanese Patent Application Laid-open No. 2006-282105 has made publicly known a shock absorbing structure for protecting a pedestrian which is configured so that: a pillar garnish for covering a front surface of a front pillar of an automobile is supported by a pillar skeletal member with a link-type pillar driving mechanism being interposed in between; in collision with a pedestrian, the pillar driving mechanism lifts the pillar garnish up from the pillar skeletal member so as to allow the pillar garnish to make stroke motions; and the pillar garnish thus absorbs the collision energy.
In the case of the invention disclosed in Japanese Patent Application Laid-open No. 2002-283939, however, it is difficult to keep the airbag deployed for a long time because the airbag is made of cloth; therefore, the airbag may not fully exhibit its shock absorbing effects depending on timing at which the pedestrian collides with the front pillar.
In the meantime, the invention disclosed in Japanese Patent Application Laid-open No. 2006-282105 has a problem that: the structure of the link-type pillar driving mechanism for movably supporting the pillar garnish with the pillar skeletal member is complicated; thus, the number of parts increases, and the cost increases.
Against this background, through Japanese Patent Application No. 2009-224381, the present applicant has already proposed an airbag system which is configured so that: instead of the conventional airbag made of cloth, an airbag made of metal is folded and arranged in a front pillar; and a gas produced by an inflator deploys this airbag toward the outside of a vehicle body.
The airbag of this airbag system is obtained by closing both end portions of a folded metal tube with respective end caps. These end caps are fixed to an attachment surface of the front pillar with bolts. Therefore, when the airbag inflates due to the gas produced by the inflator, the end caps at the respective end portions are incapable of moving in a direction away from the attachment surface of the front pillar. As a result, it is likely that: the airbag may inflate insufficiently because the both end portions of the airbag interfere with the attachment surface; and a stable deployed shape of the airbag may not be obtained because a middle part of the airbag in a longitudinal direction thereof, which is opposed to the attachment surface, is compressed and thus buckled as a result of the airbag inflating while being bent in such a shape that the middle part of the airbag in the longitudinal direction thereof moves away from the attachment surface of the front pillar.